Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22280, verified by myself.

Fix signed/unsigned comparison warnings, and shadow warnings.

WARNS=2 fixes

back out the #ifdef _DIAGNOSTIC argument checks; too many people complained.
_DIAGASSERT() is still retained.

* use _DIAGASSERT() to check pointer arguments against NULL and file
descriptors against -1 (as appropriate).
* add actual checks which to detect stuff that would trigger_DIAGASSERT(),
and attemp

* use _DIAGASSERT() to check pointer arguments against NULL and file
descriptors against -1 (as appropriate).
* add actual checks which to detect stuff that would trigger_DIAGASSERT(),
and attempt to return a sane error condition.
* knf some code
* remove some `register' decls.

the first two items result in the addition of code similar to the
following in various functions:

_DIAGASSERT(path != NULL)
#ifdef _DIAGNOSTIC
if (path == NULL) {
errno = EFAULT;
return (-1);
}
#endif

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More trailing white space.

LP64 fixes. *sigh*

- KNF
- add NetBSD comment
- use warn instead of perror
- protect overflowing the stack on bad DNS records
- delint

bzero->memset, bcopy->memcpy, bcmp->memcmp

FTP uses ruserpass() differently from that in libcompat. Fix rexec to
recognize that the new ruserpass returns an int (but ignore it for now),
and ruserpass does not accept an acct pointer.

rcsid facism, WARNSify

- convert unsafe strcpy(), strcat() and sprintf() to the `n' versions.
- some KNF.

Prototypes (PR#1098).

Fill in sin_len.

needs string.h

update